OOPS and Diagnosis help needed.

[TitanMike]

Originally Posted by camaraderie

Just a (hopefully) final update for all those who chipped in with good advise...
After fully charging the batteries...I disconnected the negative and let them sit for 5 days and just re-measured the voltage after sitting and settling and the batts are at 12.7...100% full in static measurement.
I may have some loss of capacity from the single flattening...but it is certainly not anything to worry about.
Thanks again to all.

If it's been said before it's worth repeating. The fact you got on top of the problem immediately, and let the batteries charge fully, more likely than not most if not all of the sulfate formed by the discharge was converted and any loss of capacity would be in line with what most batteries loose from age alone.

The longer a battery sits in full discharge the more capacity is lost and in many cases it won't even accept a charge.

It would be interesting to see how all the cells compare when checked with a hydrometer. Also, how much life you get out of these batteries before you need to replace them based on meeting your power needs before they hit the 50% level. Expect to hear back on this in a few years

In my first years of boondocking I had a trailer with none of today's "Whiz-Bang" technology. 120 Volt lighting if you plugged in and a propane fueled gas lamp over the dinette table. Small 12 volt fixtures in bathroom and over each bunk. To charge the battery you plugged in a separate battery charger at home or if you were in a campground.

Back in those days I ran the battery down until the lights turned a dim orange color. Usually got a week or so from a group 27 Marine battery. It was good for 3-4 years.

Today we have fancy converter/"smart chargers", all lighting is 12 V LED, inverter to run the microwave, large battery banks, only run our batteries down to 50%, yet battery life seems to be the same 3-4 years. Go figure

[camaraderie]

Originally Posted by MNtraveler

Now just one thing to save you some effort. You can skip that needlessly complicated practice of plugging the converter into an extension cord and then to a wall outlet. You can plug the RV power line straight into the wall outlet using a small 30A to 15A adapter and the converter will work just fine. It draws <10A and after a while only draws 1A steady state. And you can leave it on nonstop since it has a periodic anti-sulfation (boost) cycle. Just be sure to leave the battery switch on!

Thank you. I think this is good advise for others with the same issue...BUT ...I am in a RV storage lot exactly 50 feet away from my converter (yes it is a modern FOUR stage converter complete with desulfation cycle in addition to float.) and my 50 amp permanently attached power cord will not reach OR fit through the holes in the chain link fence that separates me from the outlet I am allowed to use occasionally overnight to keep my batts maintained.
Thanks again for the kind comments.


[Edit...actually meant the following for Wolf Whistle] I actually think I'm the first one here ever to mention Victron about 3 years ago since I used one on my boat (cruise-abloard 6 years FT with 1250 amphour bank, solar and wind + 8kw diesel genney!). At that time all the talk here was about Trimetric which I felt was a bit clunkier to install and more expensive while still being a perfectly fine product. So we agree on that one too!
As to my alternator...at 140 amps with nothing else on but the engine I got an immediate 13.6V reading vs. the 12.8 volt reading I was getting from the PD unit (at the batteries). I'm pretty convinced that the PD would not have made it alone without me running that engine alternator for a couple of hours first before shutting the engine down and using the PD alone for 24 hours.
Won't ever be sure but I was getting ZERO rise in voltage off the PD the whole time before starting the Alternator...not even a tenth...despite 13.6V at the terminal. And the little video I linked to also makes the point that a FLAT battery needs assistance first before working with a modern multi stage charger.

[camaraderie]

Originally Posted by TitanMike

It would be interesting to see how all the cells compare when checked with a hydrometer. ....

Today we have fancy converter/"smart chargers", all lighting is 12 V LED, inverter to run the microwave, large battery banks, only run our batteries down to 50%, yet battery life seems to be the same 3-4 years. Go figure

HI again Mike...I agree with your comments and I think I will do a hydrometer test. We're gonna do a short road trip in August and once I get her into a campground with a full charge, I will do the hydrometer and see how the cells in both batts balance out and report back around labor day.

Funny about the 3-4 year window... Probably why most batteries warranties...even pro rated stop at 36 months! They know we murder them!! I was almost guilty of negligent homicide!
Thanks again!

[camaraderie]

Hi WW...I'm gonna reply in red right next to the points you make below. Thanks.

Originally Posted by WolfWhistle

camaradarie, interesting thread! The initial concern was the 5% voltage drop from charger to batteries. That 13.6 to 12.8 volt drop is a bit high, but not surprising. What you went through shows the difficulty in going by volts only. Volts and current and resistance all factor in.
True...but since the voltage drop Completely disappeared in normal rather than "SALVAGE" mode...it is not really a voltage drop but rather an indicator that the charger is not working to charge the flattened batteries. Furthermore...my batteries (200 amp hours) would NEVER accept anywhere near 75 amps...maybe 50... but more likely 40 for a short time in bulk mode before changing to absorbtion. Wet cells won't take more than a .25C charge regardless of charger size. Ditto the amps from the 140 amp alternator.

But, you know quite a bit about these chemical storage things. Knew to rest them before reading, etc. Believe me when I say, I am not picking and am first to admit I am learning as I go.

Back to the issue, the sure way to know state of charge is SG. So, going back to the puzzling voltage drop... 75 amps of current, since we know the batteries were very low that charger was grunting (sorry to be so techincal LOL)... so with 4AWG wire (dunno, just guessing) I think it is about 8AG ...and 19 feet (another hypothetical) probably not far off the drop is indeed 5.21%. If the CC can make more amps than that it is easier to justify that 5% scenario.
As noted earlier, nice in theory...but I now have ZERO measureable drop in voltage on the same circuit. Whatever drom there is...is in the hundreths of a volt range.

What you need... we all need... is a good SOC true battery monitor. Victron makes a cool one that is bluetooth to a smartphone app, and there's the old standby Trimetric TM-2030. Amps, Amp/hr, W/hr its all there. Those plus a shunt and some wiring is all it takes.
After having lived with one off the grid for 6 years...I totally agree with the Victron... but in my case, when camping I am ALWAYS plugged in so my batteries are NEVER cycled unless I do something really dumb like post #1! For those who DO boondock and cycle their batteries it pays for itself easily.

I'll bet money there is nothing wrong with your Progressive charger even it is made for folks that nearly always stay plugged or go from from full-hookup to another... THAT IS ME! no reason to think an automotive charger was any better. The Progressive just needed time and you let it takes its time. No..disagree...the Progressive will NOT charge a flat battery. The charger is NOT broken...it works fine now...but it does not see and charge flattened batteries like mine were I am convinced.

The alternator helps, but with your high cranking amp battery and the deep cycles, at the same time... the alternator's goal isn't getting those deep cycles charged properly. Plus the length of the run and gauge of cable... sounds like it was shorter than the CC to battery run.
The 140 amp alternator charges the deep cycles just fine except it doesn't finish them off and maintain them...it is the exact belt driven equivalent of a constant voltage DUMB battery charger of the past. Those past dumb chargers will kill batts if left plugged in...but since their non sophisticated circuitry doesn't care what you connect to it...it CAN work and SAVE a flat battery so that you can finish the job with your smart sophisticated charger. I had heard this in the past but never before had flattened batteries enough to make this necessary. I am now a believer!
So if you have your dad's old die hard battery charger hanging around somewhere. Don't get rid of it...you may find you need it again someday if you're an idiot like me!
WW

Thanks again for your thoughtful comments.